FIG. 1 shows a conventional air fan 11 that mainly includes a frame 111 and a blade portion 112. The blade portion 112 includes a hub 112a and a plurality of blades 112b spaced around the hub 112a. The frame 111 includes a plurality of locating bars 111b, and a driving section 111a fixedly supported by the locating bars 111b to locate at a center of the frame 111 for the hub 112a to rotatably connect thereto. A lower surface 111d of the driving section 111a is flush with a bottom surface 111c of the frame 111.
Please refer to FIGS. 4 and 5 at the same time. The air fan 11 is connected to a top of a radiator 13 having a plurality of radiation fins 131. To assemble the air fan 11 to the radiator 13 for use, first extend fastening elements 12 through holes 111e provided on the frame 111 into the radiation fins 131. Thereafter, connect the radiator 13 at a bottom to a top of a chip 141 on a circuit board 14.
Please refer to FIG. 3. When the blade portion 112 is driven by the driving section 111a to rotate and produce airflows, there is a considerably large dead-air zone formed below the lower surface 111d of the driving section 111a to largely reduce the heat dissipating effect that may be achieved by the fan.
It is therefore tried by the inventor to develop an improved air fan to provide enhanced heat dissipating effect.